1. Field of the Invention
The present invention relates to a damping device, and more particularly to an adjustable hydraulic damping device with a simplified structure.
2. Description of Related Art
A hydraulic damping device is used as a shock-absorbing device on a bicycle or a flow controller in a flow discharging system. The conventional hydraulic damping device has an adjusting device for adjusting the damping effect provided by the damping device. However, the conventional hydraulic damping device with an adjusting device has a complex structure, and the cost for manufacturing the conventional damping device is excessive.
To overcome the shortcomings, the present invention tends to provide a hydraulic damping device or obviate the aforementioned problems.
The main objective of the invention is to provide a hydraulic damping device with a simplified structure. The hydraulic damping device has a cylinder, a rod, a piston, a first biasing member, a seal and a second biasing member. A top cap and a bottom cap are respectively attached to the top end and the bottom end of the cylinder. The rod moveably extends through the bottom cap and into the space in the cylinder. The piston is securely attached to the rod and is received in the cylinder to divide the space in the cylinder into a first chamber and a second chamber. The piston has multiple first channels and multiple second channels defined through the piston and communicating with the first chamber and the second chamber in the cylinder, wherein each first channel has a diameter larger than that of each second channel. Working fluid is contained in the space of the cylinder at an original pressure. The first biasing member has a resiliency and is connected to the rod to provide a recoil force to the rod. The seal is moveably mounted on the rod, and is received in the second chamber to abut the piston to close the first channels in the piston. The second biasing member has a resiliency and is mounted on the rod to provide a force to push the seal to abut against the piston. Accordingly, the hydraulic damping device has a capability of adjusting the damping effect and has a simplified structure.